The present invention relates generally to improvements in feeding and cutting control mechanisms for roll type paper and it relates more particularly to an improved control mechanism for controlling the feeding and cutting sequences of paper unwound and drawn from roll storage.
In general, a paper or sheet wound in roll form is utilized in various fields and is fed and cut to predetermined lengths. In the field of electrophotography, the paper is used as copying paper for forming a duplicate of an original to be copied thereon and various devices for cutting the copying paper drawn from a roll storage are known. One example of such a device is shown in U.S. Pat. No. 3,665,796 in which a cutter blade is operated while transporting or feeding the copying paper. In this device, a loop forming means is provided between a cutter and a succeeding transporting means for forming a loop in the paper. The cutting of the paper is accomplished while continuing the transportation by the succeeding transporting means with a loop of the paper formed by the loop forming means paid out during the cutting operation so that the paper at the cutter may be stationary. While this device effectively performs the cutting operation, the loop forming means is required and in addition, the paper cannot be transported at high speed.
Another type of cutting device hithertofore known is similar to the device described above, but without the mechanism for forming the loop. Specifically, this type of cutting device operates a cutter blade at high speed while transporting the paper and accordingly allows the cutting of the roll paper without producing an abnormal tension which would adversely effect the succeeding transporting means or the roll paper itself, and thus dispenses with any special mechanism for use in the transportation or feeding of the roll paper such as a loop forming means, with the resulting simplified construction of the machine as well as a reduction in the size thereof. However, such cutting devices suffer from a disadvantage in that after cutting, the length or amount of the leading edge of paper protruding to some extent from the cutting blade various from one cutting to another and this constitutes a critical disadvantage as the length of paper cut has a different length in each cutting due to the variances in the protruding amount of the leading edge of paper.
Various attempts have been made to overcome this disadvantage and one of such attempt is the provision of means for generating a signal for deenergizing paper feeding rollers which are located at a position preceding the cutter blade and for energizing the cutter simultaneously. However, this causes the paper to be stretched excessively during the cutting operation and results in the tearing of the paper. Another attempt is the provision of a control mechanism which includes a cam means adapted to be driven synchronously with the transportation of the paper and the generation of signals sequentially with a minor time interval for energizing the cutter and for deenergizing the paper feeding rollers. However, this control mechanism still suffers from another disadvantage in that the time taken from the input of the signals until commencement of actual actuation of the cutter blade and the paper feeding rollers are not constant from one cutting operation to another and there is always some timing errors in the actual actuations. Accordingly, when the operation of the cutter blade and stoppage of the paper feeding rollers are separately effected with such minor time interval, the rotation of the paper feeding rollers may possibly be terminated before the cutter is operated or after the cutter is operated with an unexpected long delay. These instabilities result in unevennesses or variances in length of the leading edge of the paper protruding from the cutter from one operation to another as well as other various disadvantages.